Carbon-brush connection.



' H. B. EYNON.

CARBON BRUSH CONNECTION.

APPLICATION FILED MAY I, I9I4.-

1,188,635. Patented Jun@ 27,1916.

www @was cih/wanton l. 5)/1/0/1/ @gw futon/Ie A UNITED STATES PATENTOFFICE.

HOWARD B. EYNON, 0F EAST ST. LOUIS, ILLINOIS, ASSIGNOR TO AMERICANCARBON & BATTERY CO., OF EAST ST. LOUIS, ILLINOIS, A CORPORATION OFILLINOIS.

CARBON-BRUSH CONNECTION.

Specification of Letters Patent.

Patented J une 27, 1916.

To all whom it may concern Be it known that I, HOWARD B. EYNoN, acitizen of the United States, residing at East St. Louis, county of St..Clair, State of Illinois, have invented certain new and usefulImprovements in Carbon-Brush Connections; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,Such as will enable others skilled in the art to which it appertains tomake and use the same.

It is the object of the present invention to provide an improvedconnection between a flexible conductor, such as a stranded pigtail, anda carbon block, suitable for use as a brush in motors, dynamos anddynamo electric machines. To edect a connection between the strandedconductor and the carbon block, which shall have good electricalconductivity, satisfactory mechanical strength, cheapness, permanenceand other desirable characteristics both electrical and mechanical, Imake use of anv amalgam, such as a copper amalgam, by filling a cavityin the carbon brush with the amalgam and suitably attaching the strandedconductor to the cari bon by means of this amalgam filling.

One embodiment of the present invention is disclosed in the accompanyingdrawings, wherein- Figure l is a sectional elevation through the brushshowing the amalgam lling in the cavity; Fig. 2 is a sectional plan onthe line 2--2 of Fig. l; and Fig. 3 illustrates a modification in whichthe upper portion of the cavity is filled in with a carbonaceousmaterial.

In the embodiment illustrated, the flexible conductor l is of ordinaryconstruction, as of stranded copper wire, and the carbon block 2 may beof a usual composition of carbon held with a binder and admixing withgraphite or other suitable materials in accordance with standardpractice.

To effect the connection, a straight, cy-

lindrical hole is drilled through the top of the brush, preferably of asize to just receive the stranded conductor and of a depth depending onthe size of the brush, as, for instance, one and one-half inch for motorbrushes of the more usual sizes. In addition to this drilled hole orcavity a second smaller drilled hole where it lies along one,l

side directly in contact with the copper plating. A soft and plasticamalgam is then tamped in to fill the cavity and form a plug 3 holdingthe stranded conductor tightly against the copper plating and lillingup. all interstices with metal of good conductivity.

Various amalgams can be used but a copper amalgam or copper bronzeamalgam has proved satisfactory. The preferred method of productionconsists in taking 100 parts by weight of copper bronze powder andwetting with water to a-paste and then adding 25 parts of mercury andrubbing thev material thoroughly. Some diluted sulfuric acid is thenadded and the mixture rubbed again until complete amalgamation results,after which the material is washed free of acid. The amalgam is then' ina quite porous or puffy condition and when tamped into the cavity feltstogether well and is in the right condition for establishing aconnection of high electrical conductivity between the strandedconductor and the carbon. There is enough mercury present to insuresuperficial amalgamation with the copper lining and with the copperwires of the stranded conductor, so that goodadhesion is effected; butthere is vnot enough free mercury resent to materially weaken thestrands o the conductor by union therewith. After the amalgam has beentamped in, it is allowed to harden or set, and during this hardeningoperation it expands slightly, though not enough to crack or endangerthe carbon block. This expansion tightens up the illing in the cavity.

The adhesion of the amalgam in the cavity and its intimate blending withthe stranded conductor, into the irregularities of which it percolates,insures a strong mechanical connection of good electrical conductivityand well adapted to changes in temperature and to the other tryingconditions to which motor brushes are in practice subjected.

In the modified form illustrated in Fig. 3, the amalgam plug 3 does notfill the entire cavity, but the upper portion of the cavity is filledwith a mixture 4 of carbon dust and sodium silicate, which on hardeningtightly grips the stranded conductor and assists in mechanically holdingit in the carbon block. The carbon dust is made up into a thick pastewith 280Baum sodium silicate. The amount of sodium silicate used dependsupon the fineness of the carbon dust.,

With the constructions above described, the carbon block can wear awaywhen in use without weakening the connection, and even though worn awayuntil the amalgam touches the commutator, no harm will be done, for theamalgam is softer than the commutator bars and will not scratch. Otheramalgams can be used but the composition above disclosed has manyadvantages, particularly when prepared as above set forth. If too littlemercury is used the material is too dry, and will not pack or felttogether well, and if too much mercury is used, there is danger ofimpairing the strength of the stranded conductor through amalgamation ofthe copper wires, while b keeping the proportions in about the relationctl00 parts copper, or copper bronze powder, to 25 parts mercury, thesedisadvantages are obviated and the connection is mechanicallysatisfactory; also copper amalgam has relatively-.good electricalconductivity.

Various changes in mechanical detail and in arrangement of the parts maybe made without departing from the spirit of my invention as defined bythe appended claims.

I claim:

1. The combination with a carbon brush having a cavity therein, of anamalgam plug in said cavity and a conductor secured i in good electricalconnection with said carbon brush by said amalgam plug.

2. The combination of a carbon brush having a cavity therein, .anamalgam plug in said cavity and a conductor permanently embedded inthe'amalgam to establish electrical connection with the carbon of saidbrush.

3. The combination of a carbon brush having a cavity therein, anelectro-plated lining for said cavity, a conductor projecting into saidcavity and an amalgam filling establishing good mechanical andelectrical connection between said conductor and the carbon.

4. The combination of a carbon brush drilled at the top to form acavity, a lining of electro-plated copper for said cavity, a conductorprojecting into said cavity and copper amalgam holding said conductor ingood mechanical and electrical connection with the carbon of said brush.

5. The combination with a carbon brush having a cavity therein, of aflexible conductor contacting with one side of said cavity and anamalgam filling about said conductor holding it in place, said fillingcomprising copper and mercury in about the proportion by weight of 100to 25.

6. The combination of a carbon brush having a cylindrical hole therein,a flexible stranded conductor fitting snugly in said hole, said carbonbrush having a cylindrical cav-ity into which said hole merges along oneside and an amalgam filling in said cavity holding said conductor inplace.

7. The combination of a carbon brush having a straight cylindrical'holetherein, a. layer of electro-plated copper lining said hole, a flexiblestranded conductor fitting snugly in said hole and against saidelectroplating, said carbon'brush having a cylindrical cavity into whichsaid hole merges along one side and an amalgam filling in said cavityholding said conductor in place.

8. The combination of a carbon brush having a straight cylindrical holetherein, a layer of electro-plated copper lining said hole, a flexiblestranded conductor fitting snugly in said hole and against saidelectroplating, said carbon brush having a cylindrical cavity into whichsaid hole merges along one side and an amalgam filling in said cavityholding said conductor'in place, said amalgam comprising copper andmercury in about the proportions by Weight of 10() copper to 25 mercury.

9. The combination of a carbon brush having a hole therein, a layer ofelectro-plated copper lining said hole, a flexible stranded conductorfitting snugly in said hole and against said electro-plating, saidcarbon vbrush having 'a cylindrical cavity into which said hole mergesalong one side, an amalgam filling in said cavity holding said conductorin place, said amalgam comprising copper and mercury in about theroportions by weight of -100 to 25 and a solidilied paste covering saidamalgam at the top of said, cavity.

10. The method of establishing a good electrical connection between aflexible stranded conductor and a carbon brush having a cavity,- whichconsists in lining the cavity with electro-plated copper, inserting aflexible stranded conductor therein, tamping an amalgam about theconductor and allowing the amalgam to harden and superficiallyamalgamate with said copper lining and thereby secure the strandedconductor to the brush.

11. The method of connecting a stranded conductor to a carbon brushhaving a cavity therein, which consists in electro-plating the 13 wallof the cavity with copper, inserting the end of the flexible conductorinto the cavity in contact with one side thereof, tamping a copperamalgam about the flexible conductor and allowing said amalgam to hardenand superficially amalgamate with said copper lining, and therebyestablish good electrical and mechanical connection between theconductor and the carbon of the brush.

12. The method of attaching a flexible conductor to a carbon brushhaving a cavity in the top thereof, which consists in inserting aflexible conductor therein, tamping a copper amalgam about saidconductor and allowing said amalgam to harden and expand and therebyestablish a tight connection between the conductor and the brush.

13. The method of connecting a flexible stranded conductor to a carbonbrush having a drilled hole in the top thereof, which consists inelectro-plating the cavity with copper, inserting the flexible conductorinto the cav-ity in contact with its electro-plated 1ining, tamping aper cent. copper amalgam about the stranded conductor and allowing saidamalgam to harden Superficially and amalgamate with said lining andthereby establish good electrical connection between the strandedconductor and the carbon of the brush.

ll. The method of connecting a stranded flexible conductor to a carbonbrush having in the top thereof two drilled holes offset with respect toone another and merging into one another, which consists inelectroplating the cavity thus formed with a lining of copper, insertinga flexible conductor in one of the drilled holes and positioning itagainst the electro-plated lining, tamping a Q5 per cent. copper amalgaminto the cavity and allowing said amalgam to harden and amalgamate withthe copper lining to establish a permanentconnection of goodconductivity between the stranded conductor and the carbon of the brush.

In testimony whereof I alix my signature, in presence of two witnesses.

HOWARD B. EYNON.

Witnesses CARL HAMBnUoI-rnn, OTTO NOLL.

Copies kof this patent may be obtained for tive cents each, byaddressing` the Commissioner of Patents,

Washington, D. c.

